I’m a bit confused by the switch on the back of my Fryette Fatbottom 2x12 Cab. There is not user manual and I’ve looked around for more information, but have not found it.
This cab is loaded with 16 Ohm F70G. Mono Input A says 8 Ohm and 16 Ohm Stereo. Then Input B says 16 Ohm Stereo, 8 Ohms linked. What does 8Ohms linked mean? I also use a PS-2A and up until recently I just run the and 8Ohm connection to input A on Mono. No issue there.
I recently ordered 8 Ohm speakers and loaded it in the fatbottom cab. I would be safe to assume that the above stated impedance values are now cut in half? I’m not sure if I was a fan of the 4Ohm Mono sound, so what I did was use both speaker outs on the PS-2A and set it to 8Ohm out, flip the switch on the back on the cab to stereo and plug into Input A and B from the PS-2A. Is this correct? I don’t want to damage the PS-2A or the speakers.
The Mark V amp connected to the PS-2A tubes, input and output transformers get pretty hot. I know heat dissipation is to be expected, but I don’t want to cause damage.
Answers to the above questions would be appreciated. Thank you Team Fryette or anyone else who chimes in!
Linked is just parallel, same as when you plug into the mono side just stated as if you are using two outputs like what’s on your PS-2A. As for your second question, if you install two 8 Ohm speakers, your mono input will be 4 Ohms and using two speaker outputs on the PS-2A will also be 4 Ohms. When using two speaker outputs, you’ll always have to adjust for the impedance of both speakers. 8 Ohms and 8 Ohms is still 4 Ohms parallel, even if done from the PS-2A.
Thanks for the quick response and the warm welcome!
I’m still confused why does the cab have 16Ohms on the stereo/linked side if you say it’s in parallel? In linked/stereo operation on the cab - am I right in putting two loads on input A and B ? If there are 8Ohm speakers in there now, would running cab switched to stereo expect to see a 8Ohm load for each input, right?
16 Ohms per side stereo. Linked is different. It’s why there are two different ratings. If you’re running a stereo power amplifier “linked” it is the same impedance as running a mono power amplifier with two speakers in parallel. That’s how you get 8 Ohms.
The cab may be switched to stereo, but the amplifier is still seeing a parallel load. The jacks on the PS-2A are wired in parallel. If you plug an 8 Ohm speaker into each jack, the amplifier sees 4 Ohms, not two separate 8 Ohm loads. If you were running a stereo power amplifier, you could set each channel for 8 Ohms.
It’s making a bit more sense now… so is the way I have it hooked up now, dangerous or likely to cause long term damage? Should I just go back to setting the PS-2A to 4Ohms on the switch and running this cab in mono 4ohm?
Yes, if your running a 4 Ohm 2x12, the best bet is to run the Power Station at 4 Ohms as well.
This is an excerpt from our ZMACS manual that will explain mismatch a bit better:
“Choosing the correct operating impedance to match the selected amp to the destination cab or load ensures maximum tube life and transparent sound quality. For the most part, running a mis-match between an amplifier and cabinet is not inherently dangerous unless you are cranking the amp to maximum output or very nearly to it. However, there will be a noticeable tonal shift when, for example, running an 8-ohm amp into a 16-ohm cab.”